Option to become a supported without donation?

Is there an option to support a fundraiser without a monettary donation?

We organize walks where we would like people to join them either with a donation or without and then we would like to list them in a similar way as you have on this page: https://cure.org/my/tebow/

Basically, we just want the people to register for a fundraiser and come out for a walk to support us. Donation should be an option during the registration and not required.

What options do I have?

Thanks for a great plugin!

https://www.ads-software.com/plugins/personal-fundraiser/